[Antennas] Mast question

[Manish]

Hi all,         I wanted to know if  some one can help me out with a mast
related question.
I intend using a  single 18-20 feet galvanized iron mast with a  base made
up of 3 pieces  at 120 degree spacing ( similar to mercedes benz logo or a
 spread out tripod). additional support will include a  tripod like
structure about 2 feet above from the base running to the spread out
structure. There will be  at least 2  guy posts along the length of the
mast.

The base and the mast are not welded or  joined in any way .The base support
structure will have a  bearing sort of orifice to insert the mast into.This
way  locally available  sturdy bamboo can be used - if  need be ( for a
 field op or emergency)

The question is  - any suggestions/ modifications  to this design ?
This  entire structure will stand on the roof ( about 20 feet  above ground
) effective height at feed point of antenna will be 40 feet more or less.
This mast will use an off center fed dipole with a ladder  line.

Thanks in advance.
73's
VU2MTQ
Manish